Running the mechanical dehumidifier is a great way to measurably lower the relative-humidity in a boat. I strapped them down when I used them on my larger, previous boats for over 30 years. They were wet-slipped in a marina and later in the canal at my home. I used then mostly just in the winters here, when our highest relative-humidity's occur. (yes, in 'mixed-climates' the highest relative humidities occur on winter mornings, not on hot summer days). Another nice 'side-effect' of the mechanical dehumidifier is that it produces heat. (A mechanical dehumidifier is actually just an 'air-conditioner', except unlike an air-conditioner, it does not dump the 'heat' outdoors. It stays in the room). It uses a compressor and a coil to produce a cold surface/coil, and that coil/surface becomes the 'iced tea glass'; it sweats/rains/reaches dew-point/condensates, and then drains the 'water' out the hose, then out of the boat. The other side-benefit, better said, double-benefit of not dumping the heat outside, is when you RAISE the temperature of any volume of air, at any relative humidity, you LOWER the relative humidity of that air, so a mechanical dehumidifier 'lowers relative humidity' in TWO ways; and mold and/or mildew cannot grow below 70 % relative humidity. (I use 60-65 % to add a buffer/safety margin. But ideal humidity for humans and other animals is 50%
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